Question

How will the tendency to gain electrons change as we go from left to right across a period?

Answer 1

As we go from left to right across a period, we find that the number of electrons in its outermost shell and the size of the atom decreases. Due to the following reason as we go across the period from left to tight, we see that the tendency to gain electrons increases.

Complete answer:
There are a lot of elements present in this world, some exist independently, while some exist as an impurity, some as a mineral of two elements and of some we find only traces. All these elements were being discovered but didn’t have any order or a table to analyse them. That table of elements on this earth known to us of existence is called the periodic table.
This periodic table is further divided into periods and groups. There are seven periods and eighteen groups. Period is the horizontal row of the periodic table.
As we go along the group starting from the first period, we observe that the number of electrons increases. Therefore, from the left to write the number of electrons. Eg. Hydrogen has more electrons from helium, hydrogen has one and helium has two.
Therefore, as we go across the period there is an increase in electrons and protons. Now the protons increase in the nucleus, which increases its strength and therefore the size of the atom keeps on increasing. As the size of the atom decreases and its power increases to attract electrons, we can say that as we go from left to right along a period the tendency to gain electrons increases.
As we go from left to right along a period the tendency to gain electrons increases.

Note:
The thing to note is that the last group of the periodic table has noble gases. Now noble gases are those which have their outermost orbital filled and therefore they don’t have any tendency to gain electrons or to even lose electrons because they are in their most stable state.